When lettuce is cut it exudes a milky juice, which is why the ancient Romans called the plant lactuca, a name derived from the Latin lac, meaning milk. The word was introduced to English in the late thirteenth century, but the English did not commonly cultivate it in their gardens until the fifteenth century. Words related to lettuce include lactic acid, a substance that forms in milk when it sours, and galaxy, so called because the distant regions of our own galaxy—the Milky Way—stretch across the night sky like a creamy band.
There exist multiple species of leafy plants that contain a milky juice and are frequently utilized in salads. These variants include Bibb, romaine, leaf, Boston, and head, or iceberg lettuce. The term “butter lettuce” is occasionally employed in a loose fashion, as a means of distinguishing any of the softer and more delicate types of lettuce from the sturdier head lettuce.
Lettuce, a vibrant green plant, is primarily used as a salad ingredient, although it can also be cooked and served as a vegetable or transformed into soup. It encompasses several species and approximately a hundred varieties, which are classified into five distinct classes: Crisp-head, characterized by a firm head and a brittle texture; cos or romaine, featuring a long-shaped head and narrow leaves that can be self-closing or loose-closing; butterhead, with soft leaves and a delightful buttery flavor; leaf lettuce, which does not form a compact head; and stem lettuce, with celtuce being the only variety available in the United States. Among the crisp-head lettuces, which hold significant commercial value in the United States, iceberg lettuce is the most well-known. As for the butterhead lettuces, Boston and Bibb varieties take the lead.